This invention relates generally to remote monitoring and diagnostics, and more specifically relates to telemetry of diagnostic messages from a mobile asset to a remote service center. One embodiment of the present invention is a telemetry system employing airborne sensors and telemeters to transmit maintenance data (such as performance data of an aircraft engine) from an aircraft-in-flight to a ground based service center.
Remote monitoring and diagnosing of the condition, performance, and failure of parts, equipment and systems carried by mobile assets such as airplanes, turbines, locomotives and medical systems is becoming increasingly important as industry struggles to improve safety, reduce maintenance costs and deliver efficient, timely and cost effective maintenance services to its customers. For that reason, remote maintenance services are seen by today's service oriented businesses as an important growth area. Remote monitoring and diagnosing capability is quickly becoming a key element in providing high-technology, value-added services for an installed equipment base which equipment base may include mobile assets such as power generation equipment, aircraft engines, medical imaging systems, and locomotives.
By monitoring the performance of such equipment and systems, an indication that a system is malfunctioning can be obtained. By providing diagnostic messages which contain information about a malfunctioning system, a measure of safety is obtained that can be of particular importance in ensuring the system is capable of performing as required. In addition, such information can be utilized to initiate a maintenance cycle before placing the system into a subsequent cycle of operation.
Control systems for devices such as turbines used for generation of electricity or turbines used in aircraft engines typically monitor a variety of turbine performance parameters, including speed, temperatures, and stresses on the turbine assembly. Prior art systems provide for monitoring these parameters in flight. However, many of the problems associated with relaying these parameters to a ground service center while the aircraft is in flight remain to be solved.
A significant problem encountered in the art of wireless digital communications of performance parameters relates to the frequency and, more importantly, the power at which telemetry devices can transmit RF signals. Until the enactment by the Federal Communications Commission (FCC) of Part 15.247 of the FCC Rules and Regulations, aircraft telemetry systems were primarily limited to the VHF band (174-216 MHz), and could only operate at very low transmission powers of less than 0.1 milliwatts (mW). (See FCC Part 15.241.) This restriction on the transmission power has significantly limited the transmission range (i.e., the maximum distance between the transmitter and the receiver) of airborne telemetry devices. Restrictions also place limits on the data rate or "bandwidth" at which the telemetry devices can transmit data.
Because of these factors the frequency bands available for transmission of information from an aircraft to ground, and vice versa, is limited. Further, there are increasing demands for other types of communications, such as voice, to utilize these available regulated bands. Adding diagnostic information channels often requires modifications to the airframe of the aircraft to add additional antennas. Because of the cost of these structural modifications, and the high recurring cost of acquiring transmission time for relaying flight performance data in the regulated frequency bands, there is a pressing need for improved systems and methods for transmitting aircraft diagnostic information from an aircraft to a ground station.